The present invention relates to polyol dispersions with long-term stability, to cellular polyurethane moldings produced therewith, to processes for their preparation and to their use.
DE-A 2 307 589 describes the production of easy-release polyurethane moldings (PUR moldings) using polyisocyanates modified with fatty acid esters. DE-A 2 121 670 discloses the production of easy-release PUR moldings using special release agents introduced into the reaction via the polyol. To achieve a substantial release effect, the release agents are preferably added to both the isocyanate component and the polyol component before they are reacted together.
In recent years, attempts have been made preferentially to dispense with the conventional physical blowing agents in the production of PUR moldings. When using water as the blowing agent, however, the conventional polyol formulations tend to exhibit greater instability and more rapid phase separation, so either they cannot be stored for long periods or expensive measures have to be taken to prevent phase separation.
The object of the present invention was therefore to provide polyol formulations for the production of cellular polyurethane moldings with good release properties which, although they contain water as the blowing agent, are sufficiently stable and only exhibit phase separation after prolonged storage, if at all.
Surprisingly, it has been found that, by using specific release agents, not only is a good release of the molding assured, but also the polyol formulation prepared which contains these mold release agents, is stable and only tends to exhibit phase separation after a prolonged period, if at all.